Endogenous and exogenous shifts of attention were
examined in nondemented patients with Parkinson's
disease (PD). In the endogenous condition, an arrow was
used to cue participants' attention to the possible
location of an impending target, whereas in the exogenous
condition, a brightened box was used to cue attention.
Cues were either valid (i.e., the target appeared in the
cued location) or invalid (i.e., the target appeared in
a noncued location). The time between cue onset and
target onset (stimulus onset asynchrony or SOA) was
varied in each condition. The results indicated that PD
patients were not differentially impaired in shifting attention
at the shorter SOAs relative to normal controls. However,
at longer SOAs, the PD patients demonstrated less of an
effect from cueing than did the normal control participants.
PD patients' differential effect from cueing was evident
in both exogenous and endogenous conditions. These results
suggest that PD patients may experience a rapid decay of
attentional inhibition and do not support the notion that a
decrement in processing resources underlies their attentional
deficits. Moreover, these findings further support the notion
that the basal ganglia may play an important role in attentional
functions. (JINS, 1997, 3, 337–347.)